The present invention relates to an electromagnetic diaphragm pump. More particular, this invention relates to a small-sized, light-weight electromagnetic diaphragm pump suitable for an outdoor air blower.
In general, an electromagnetic diaphragm pump comprises an oscillator, which has at its central portion two permanent magnets arranged to have mutually opposite polarities and is supported at both ends by diaphragms, and electromagnets disposed to be opposed to each other with the oscillator interposed. When an AC is supplied to the electromagnets, the polarities of the electromagnets are alternately changed according to the frequency of the AC. Consequently, the permanent magnets are attracted and repelled by the electromagnets each time the polarities of the electromagnets are changed. The diaphragms are vibrated by the axially moved oscillator.
Each diaphragm serves as a support member for the oscillator and constitutes a wall defining a compression chamber. With the vibration of the diaphragm, the volume of the compression chamber increases and decreases. Accordingly, fluid is drawn into the compression chamber via an inlet port formed in another wall which defines the compression chamber along with the diaphragm, and the fluid is discharged from an outlet.
FIGS. 19 to 21 show a specific structure of a conventional electromagnetic diaphragm pump (hereinafter referred to merely as xe2x80x9cpumpxe2x80x9d). FIG. 19 is a cross-sectional view showing the pump from above, FIG. 20 is a cross-sectional side view, and FIG. 21 is a left-hand side view of FIG. 20.
A pump 1 has a housing constituted by a frame 2, a soundproof cover 3 and head covers 4, 5 arranged on the left and right sides of the frame 2. Each of the head covers 4 and 5 is fixed to the frame 2 by four screws 4a, 4b, 4c, 4d; 5a, 5b, 5c, 5d (two screws 5a, 5b alone being shown). Core holders 6, 7 are erected on a bottom portion of the frame 2. Two field cores 8, 9 having the same size are supported by the core holders 6, 7 and fixed on the frame 2 by screws 8a-8c; 9a-9c. Coils 10, 11 are wound around the field cores 8, 9. An oscillator 12 is provided between the field cores 8, 9. Since the structure for attachment of diaphragms 15a, 15b fixed to both ends of the oscillator 12 and internal structures of the head covers 4, 5 covering the diaphragms are common on the left and right sides of the oscillator 12, the left-hand structure alone shown in the figures will be described and a description of the right-hand structure is omitted.
A pair of center plates 13, 14 are fixed to an end portion of the oscillator 12. The diaphragm 15a is clamped between the first and second center plates 13, 14. The diaphragm 15a has a disc shape, and its outer peripheral portion, that is, a rim portion, is clamped by a ring 16 fitted in the frame 2 and the head cover 4. Specifically, the oscillator 12 is fixed and supported at both ends by the diaphragms 15a, 15b and supported onto the frame 2.
A compression chamber 17 defined by the diaphragm 15a and head cover 4 is disposed at the end portion of the oscillator 12. A pair of inlet ports 19 for drawing air into the compression chamber 17 are formed in one of walls defining the compression chamber 17. The inlet ports 19 are provided with plate-like valve members which are bent towards the compression chamber 17 to open the inlet ports 19. This one of the walls is also provided with a pair of outlet ports for forcing the compressed air out of the compression chamber 17. The outlet ports 20 are provided with plate-like valves which are bent away from the compression chamber 17 to open the outlet ports 20.
The head cover 4 is provided with an inlet nipple 21 for drawing air and an outlet nipple 22 for discharging compressed air. An inlet chamber 23 is provided between the inlet nipple 21 and inlet ports 19, and an outlet chamber 24 is provided between the outlet nipple 22 and outlet ports 20. Permanent magnets 31, 32 magnetized to have mutually opposite polarities are fixed to the oscillator 12. An AC is supplied from an AC power supply (not shown) to the coils 10, 11 over a cable 33. The cable 33 is covered with a protection tube 34, introduced into the pump 1, divided into a plurality of coil lead wires 35 within the pump 1, and connected to the coils 10, 11.
The pump 1 is fixed to a bracket 41 via legs 40 formed of elastic material, such as rubber, for vibro-isolation. The bracket 41 is attached to a desired location and the pump is driven.
When an AC with a commercial power frequency is supplied to the coils 10, 11 over the cable 33, the pump starts to operate. With the supply of AC, both end portions of the E-shaped main cores 8, 9, i.e. those portions thereof opposed to the oscillator 12, are caused to have magnetic poles alternately with polarities for attracting and repelling the permanent magnets fixed to the oscillator 12. The oscillator 12 vibrates in the right-and-left direction at the aforementioned commercial power frequency. In accordance with the vibration, the diaphragms 15a, 15b take in air from the inlet nipple 21, inlet chamber 23 and inlet ports 19 and compress the air in the compression chamber 17. The compressed air is discharged via the outlet ports 20, outlet chamber 24 and outlet nipple 22.
When a large discharge amount is to be obtained using the pump of the above type, it is thought to couple of a plurality of this type of pumps. For example, if two pumps each having a discharge amount of 40 l/min. are coupled, a discharge amount of 80 l/min. is obtained. Jpn. Pat. Appln. KOKAI Publication No. 61-207883 proposes an electromagnetic reciprocal pump wherein a plurality of pumps are coupled. The following problems, however, will arise if a plurality of electromagnetic diaphragm pumps are coupled.
Although a discharge amount can be increased by integrally coupling plural pumps, the size of the apparatus increases accordingly. Where a plurality of pumps are integrally coupled and used as an outdoor blower, etc., an enclosure has to be provided for preventing dropping. In such a case, in particular, the size of the apparatus including the enclosure increases and the location for installation is limited. Under the circumstance, there is a demand for reduction in size. In addition, the electrical wiring among the plural pumps becomes complex.
Besides, the diaphragms used in the pump are worn due to long-time use, and they need to be replaced with new ones periodically. In the case of the apparatus in which plural pumps are merely coupled, the housing of each pump needs to be disassembled for exchanging the diaphragms. As a result, the number of steps for maintenance increases.
Even in the case of driving a single pump, the following problems will arise.
First, since two field cores 8, 9 of the same size, around which coils are wound, are disposed in the pump, the size of the pump increases and the weight of the pump also increases.
Second, since many screws are used to fix the field cores 8, 9, head covers 4, 5, etc. to the frame 2, the assembly work becomes complex and the cost of the pump increases. For example, six screws (8a-8c; 9a-9c) are used to fix the field cores 8, 9, and eight screws (4a-4d; 5a-5d) are used to fix the head covers 4, 5.
Third, great vibration noise of the diaphragms leaks to the outside via the chamber containing the field cores 8, 9.
Fourth, since the size of the pump is large, as mentioned above, the buffer vessel for smoothing the pulsation of compressed air needs to be connected to the outlet nipple 22 via a pipe. This increases the size of the apparatus, makes the structure complex, and increases the cost. Moreover, the space for installation of the pump and buffer vessel increases.
The present invention has been made in consideration of the above circumstances, and a main object of the invention is to provide a small-sized, light-weight electromagnetic diaphragm pump which permits easy maintenance.
More specifically, with this main object taken into account, this invention aims at providing a small-sized, large-output electromagnetic diaphragm pump having one or more compression sections each functioning like a conventional independent pump.
Another object of the invention is to provide an electromagnetic diaphragm pump permitting easy assembly.
Still another object of the invention is to provide an electromagnetic diaphragm pump wherein vibration noise of diaphragms is small.
Still another object of the invention is to provide an electromagnetic diaphragm pump requiring no large cost and space for a buffer vessel for smoothing pulsation of compressed air.
In order to achieve the above objects, according to an aspect of the present invention, there is provided an electromagnetic diaphragm pump having an AC power supply and a plurality of compression sections operated by an AC supplied from the AC power supply. Each of the compression sections comprises: a housing; an oscillator disposed within the housing and holding a permanent magnet; a pair of diaphragms each having a peripheral portion fixed to the housing and a central portion fixed to an end portion of the oscillator. Each of the diaphragms supports the oscillator so as to be able to vibrate in a direction perpendicular to a plane in which the diaphragm is disposed. Each compression section also comprises a pair of field cores sandwiching the oscillator and having magnetic poles displaced relative to the permanent magnet by a predetermined amount in a direction of vibration of the oscillator; coils supplied with an AC from the AC supply to produce magnetic fluxes at the field cores; compression chambers defined within the housing to be opposed to end portions of the oscillator, one of walls of each of the compression chambers being formed by an associated one of the diaphragms; and inlet ports with valves capable of drawing air into the compression chamber; and outlet ports with valves capable of forcing air out of the compression chamber. The inlet ports and outlet ports being formed within the housing. The field cores have the magnetic poles magnetized by the AC supplied to the coils, whereby the permanent magnet is alternately attracted and repelled by the magnetic poles to vibrate the diaphragms. Adjacent two of the compression sections have one shared field core.
According to this electromagnetic diaphragm pump, the permanent magnet of the oscillator is alternately attracted and repelled by the magnetic poles magnetized by AC, and the oscillator vibrates. The diaphragms supporting the oscillator on the housing vibrate along with the oscillator, and the compression chambers expand and contract. Thereby, fluid flows into the compression chambers, and compressed fluid is discharged from the outlet.
Although the discharge volume is increased by the plural compression sections, the number of field cores can be reduced and the entire apparatus can be reduced in size and weight.
It is preferable that the AC supply has a circuit for supplying half waves of the AC to the coils such that at least one of the plurality of oscillators is displaced in a direction opposite to the other oscillators. Unlike the case where all oscillators are displaced in the same direction at a time, unbalanced forces cancel one another and vibrations are reduced.
Preferably, the housing has head covers integrally covering a plurality of the diaphragms of adjacent ones of the compression sections and constituting the other walls of the compression chambers of the adjacent compression sections, and the inlet ports and the outlet ports are formed in the head covers. In this case, plural diaphragms can be accessed by removing a single head cover.
The coils may be wound around one of the pair of field cores. In this case, since a field core with no coil is included, the entire apparatus is reduced in weight and size.
According to another aspect of the invention, there is provided an electromagnetic diaphragm pump comprising: a housing; an oscillator disposed within the housing and holding a permanent magnet; a pair of diaphragms each having a peripheral portion fixed to the housing and a central portion fixed to an end portion of the oscillator, each of the diaphragms supporting the oscillator so as to be able to vibrate in a direction perpendicular to a plane in which the diaphragm is disposed; a pair of field cores sandwiching the oscillator and having magnetic poles displaced relative to the permanent magnet by a predetermined amount in a direction of vibration of the oscillator; a coil supplied with an AC to produce a magnetic flux at the field core; compression chambers defined within the housing to be opposed to end portions of the oscillator, one of walls of each of the compression chambers being formed by an associated one of the diaphragms; and inlet ports with valves capable of drawing air into the compression chamber and outlet ports with valves capable of forcing air out of the compression chamber, the inlet ports and outlet ports being formed within the housing, wherein the field cores have the magnetic poles magnetized by the AC supplied to the coil, whereby the permanent magnet is alternately attracted and repelled by the magnetic poles to vibrate the diaphragms.
The pair of field cores comprise an E-shaped main core around which the coil is wound and which has a central leg portion, and an E-shaped back core around which no coil is wound, the E-shaped back core being disposed to be opposed to the E-shaped main core. According to this electromagnetic diaphragm pump, the back core contained in the housing and the housing can be reduced in size, without decreasing the output performance of compressed fluid in the pump.
It is preferably that each of the main core and the back core has a leg portion projecting toward the oscillator, the leg portion of the main core having a length greater than a length of the back core. The field core can be reduced in size and weight.
It is preferable that a distance between the main core and the oscillator is greater than a distance between the back core and the oscillator. In this case, the force of the main core acting on the oscillator is substantially equalized to the force of the back core acting on the oscillator. The vibration of the oscillator can be made smooth, and the life of the diaphragms fixed to both ends of the oscillator can be increased.
It is preferable that the housing includes a plurality of side walls, a bottom wall, and a plurality of slitted ribs extending from the bottom wall near the side walls, and the pump is provided with a cap having a plurality of downwardly extending bosses formed at locations corresponding to the slitted ribs, wherein when the bosses of the cap are inserted in the slitted ribs of the housing, the slitted ribs are extended outward to fix at least one of the main core and the back core to the housing. In this case, the cores can be fixed without using screws. Since there is no need to form holes for passing screws, unlike the prior art, the effective magnetic paths of the cores can be improved.
It is preferable that the main core and the back have, at their portions coming in contact with the slitted ribs, grooves extending in the same direction as the slitted ribs and having shapes corresponding to shapes of parts of outer peripheral portions of the slitted ribs. In addition, it is preferable that the cap has a plurality of hooks at a peripheral portion thereof, the hooks extending in the same direction as the slitted ribs, the cap being secured to the housing by means of the hooks. This cap can be fixed to the housing without using screws.
There is also provided an electromagnetic diaphragm pump having a housing which includes opposed side walls, a plurality of hooks extending outward from the side walls to accommodate the oscillator, the field cores and the coil, and head covers coupled to the opposed side walls of the housing. The head covers have hook receiving holes at locations opposed to the hooks formed on the housing, the head covers being coupled to the housing when the hooks are inserted in the hook receiving holes. The head covers can be secured to the housing without using screws.
It is preferable that the housing has guides extending from the opposed side walls in the same direction as the hooks and functioning as fluid inlets, and the guides guide the head covers when the head covers are coupled to the housing.
There is also provided an electromagnetic diaphragm pump having a housing which includes opposed side walls, head covers coupled to the opposed side walls of the housing and having outlet nipples for discharging compressed fluid, and a buffer vessel directly connectable to the outlet nipples, the housing accommodating the oscillator, the field cores and the coil. In this pump, the buffer vessel can be directly coupled to the housing. Unlike the prior art, there is no need to couple the buffer vessel to the housing of the pump via a pipe. Thus, the pump and the buffer vessel can be integrally constructed as a compact unit.
Where the electromagnetic diaphragm pump further comprises gaskets attached to the outlet nipples and each having a bottom wall and a side wall and at least one of the bottom wall and side wall of each gasket has plural small holes, the beat noise of valves transmitted to the buffer vessel can be reduced and a silent pump can be provided.
There is also provided an electromagnetic diaphragm pump having a housing which includes a housing having opposed side walls, the housing accommodating the oscillator, the field cores and the coil. The oscillator has end portions penetrating the side walls, the side walls have diaphragm receiving walls for receiving the diaphragms fixed to the end portions of the oscillator, and each of the diaphragm receiving walls has an opening with the same size as a cross section of the oscillator. According to this pump, since the hole formed in the diaphragm receiving wall is much smaller than the hole in the prior art, vibration noise of diaphragms leaking to the outside through the housing can be greatly reduced and a silent pump can be provided.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.